Filiform elements usable for reinforcing moldable materials, particularly concrete

ABSTRACT

Filiform element usable for reinforcing moldable materials particularly concrete, said filiform element having crimpings or corrugations distributed over its length, showing the following features: maximum wave amplitude of the longitudinal axis: 1 to 1.5 d; maximum wave-length: 10 d; minimum wave-length: 7 d; maximum fiber length: 65 d; minimum fiber length: 45 d; fiber diameter (d): max. 1.2 mm; nature of the steel: ultimate tensile strength higher than 110 kg/mm 2  and lower than 150 kg/mm 2 .

The present invention relates to filiform or thread-like elements,termed fibers, which may be used for reinforcing moldable materials withbinder of the hydraulic or non-hydraulic type.

Among the various types of fibers which may be used for such areinforcement, there is a family of filiform fibers of variousdimensions provided with uniform corrugations distributed over theirlength.

Prior art fibers of this family cannot be effective in reinforcingconcrete. Indeed, in order to ensure a satisfactory anchoring, inmaterials to be reinforced, there have been used corrugations of highamplitude and small wave-length. Such geometrical characteristics causevery important processing difficulties when these fibers are mixed withconcrete due to their very strong tendency to ball together i.e. tocling to one another to form balls of fibers tangled up in the concrete.These processing or working difficulties have doomed the use of thistype of fibers.

However, after study of all factors governing the reinforcement ofstone-like materials by means of fibers of said family, it becamepossible to conceive a corrugated or crimped fiber of the kind describedwhich has optimum features and distinguishes from the prior art fibersby a true concrete-reinforcing effect without the previously encounteredprocessing difficulties.

In order to achieve such a conception, it has been necessary to studythe influence of the following factors:

wave amplitude

wave-length

fiber length

fiber diameter

nature of the component steel mainly characterized by its tensilestrength

strength or resistance of the matrix itself which needs to bereinforced.

In order to guarantee an efficient reinforcing effect, for example inconcrete, it is necessary that the fibers remain anchored thereinwhichever be the stress applied thereonto. This condition is fulfilledwithout creating any processing or working difficulty if one adopts thefollowing characteristics for reinforcing a conventional concrete asused in building:

    ______________________________________                                        maximum wave amplitude of longitudinal                                                                1 to 1.5 d                                            axis:                                                                         maximum wave length:    10       d                                            maximum fiber length:   65       d                                            minimum fiber length:   45       d                                            nature of the steel: its ultimate                                             tensile strength is higher than 110 kg/mm.sup.2                               and lower than 150 kg/mm.sup.2                                                fiber diameter (d)      max. 1.2 mm                                           ______________________________________                                    

Example of optimum fiber for use in an amount of 20 to 40 kg/m³ ofconcrete or 0.25 to 0.5% by volume depending on the type of concreteelement to be reinforced:

    ______________________________________                                        diameter             1      mm                                                wave amplitude       1      mm                                                wave length          8      mm                                                fiber length         60     mm                                                ultimate tensile strength                                                                          130    kg/mm.sup.2.                                      ______________________________________                                    

In the accompanying drawings:

FIG. 1 represents a crimped or corrugated fiber at scale 1/1;

FIG. 2 represents at greater scale a portion of the fiber illustrated inFIG. 1.

There is shown the diameter d, the wave length λ and the amplitude a.

The waves or crimpings are obtained in a manner known per se.

Thus, for example, a coiled wire is uncoiled and profiled in continuousway to form corrugations by passing between rotating male and femalerollers of appropriate profile. The wire is thereafter cut to lengththrough a pair of rotating wheels the one of which is toothed and theother of which is smooth, the rotational speed of said wheelsdetermining the length of cut wire.

It should be understood that the invention is not restricted to theabove-described details which are given only by way of example.

We claim:
 1. Fiber of steel wire usable for reinforcing moldablematerials particularly concrete, said fiber having uniform wave shapedcorrugations distributed over its length, with the following features:

    ______________________________________                                        maximum wave amplitude 1 to 1.5 d                                             maximum wave-length    10 d                                                   minimum wave-length     7 d                                                   maximum fiber length   65 d                                                   minimum fiber length   45 d                                                   fiber diameter (d)     max. 1.2 mm                                            nature of the steel: ultimate                                                 tensile strength higher than                                                                         110 kg/mm.sup.2                                        and lower than         150 kg/mm.sup.2.                                       ______________________________________                                    


2. Fiber according to claim 1, characterized by:

    ______________________________________                                        a diameter of           1      mm                                             a wave amplitude of     1      mm                                             a wave-length of        8      mm                                             a length of             60     mm                                             steel having an ultimate tensile strength of                                                          130    kg/mm.sup.2.                                   ______________________________________                                    


3. Fiber according to claim 2, when used in an amount of 0.25 to 0.5% byvolume in a conventional concrete for building.